The present invention relates to a transducer for generating ultrasonic wave energy, and in particular relates to a transducer which can generate a convergent ultrasonic wave.
Although a medium is opaque optically, it is possible to view the internal structure of said medium as long as the medium is acoustically transparent; as in x-ray photography. Photographs produced using ultrasonic wave energy are applicable to those fields where the medium is optically opaque, including medical applications, microscopes, nondestructive testing, underwater observation, and/or earthquake research.
Various ultrasonic wave transducers for the generation of a focused ultrasonic wave have been proposed. Some of them utilize an acoustic phase shift plate, a circular array, an acoustic lens, or a photo-acoustic transducer. However, the above prior art techniques are insufficient or unduly complicated for focusing ultrasonic waves in the application of viewing the internal structure of a medium.